Motor

Abstract

A cup ring and a holding-plate are disposed at each side of a front bracket of a stator of a motor, to fix in place an outer ring of a front ball-bearing of the rotor of the motor in order to prevent creep between a bearing housing and the outer ring. A thickness of a bearing shim is adjusted such that a distance between an end portion of a tube section of the cup ring and a first end face of the outer ring is less than 0.1 mm. The holding plate is temporarily fixed to a given place of the motor shaft, and then screwed down thereto with a screw, so that the holding plate moves and solidly contacts the outer ring of the front ball bearing. An outer diameter of the motor shaft extending between the given place and the bearing is smaller than a center hole of the holding plate such that the holding plate does not contact the motor shaft.

What is claimed is:  
     
       1. A motor comprising: 
       (a) a rotor including a front ball bearing and a rear ball bearing both being fixed to a motor shaft;  
       (b) a stator including a front bracket and a rear bracket, the front ball bearing being positioned in a front bearing housing of the front bracket, and the rear ball bearing being positioned in a rear bearing housing of the rear bracket;  
       (c) a bearing shim;  
       (d) a cup ring having a flange section and a tube section, the cup ring being provided at least partially within the front bearing housing such that the flange section is in contact with a surface of the front bracket, and an end portion of the tube section in contact with a first end face of an outer ring of the front ball bearing via said bearing shim;  
       (e) a holding plate in contact with a second end face of the outer ring of the front ball bearing, and  
       (f) at least one fastener coupling either said flange section to said front bracket or said front bracket to said holding plate, such that the cup ring and said holding plate are provided on opposite sides of the front bracket, thereby holding the outer ring of the front bearing between the cup ring and said holding plate.  
       said bearing shim being provided between the end portion of the tube section and the first end face of the outer ring of the front ball bearing, said at least one fastener being tightened such that a distance between the end portion of the tube section and the first end face of the outer ring of the front ball bearing is less than or equal to 0.1 mm.  
     
     
       2. The motor of  claim 1 , wherein 
       inner rings of the front ball bearing and the rear ball bearing are press-fitted to the motor shaft; and  
       an outer ring of the rear ball bearing is fixed to the rear bearing housing of the rear bracket.  
     
     
       3. The motor of  claim 1 , wherein 
       the motor shaft includes a section, near a rear end of the front ball bearing, of which rim is fit into a center hole of said holding plate, and an outer rim of the motor shaft extending between the section and the front ball bearing is smaller than the center hole of said holding plate.  
     
     
       4. The motor of  claim 2  further comprising a helical gear mounted to the motor shaft. 
     
     
       5. The motor of  claim 2  further comprising an optical encoder mounted to the motor shaft at an outside of the rear ball bearing. 
     
     
       6. A diaphragm pump that employs the motor of  claim 1 . 
     
     
       7. A diaphragm pump that employs the motor of  claim 2 .